Transients Induced in Control Cables Located in EHV Substation

This paper was prepared from data collected in tests made to evaluate the effectiveness of shielding control cables that are laid in concrete trenches located in an EHV environment. Particular attention is given to the effectiveness of shielding against high frequency transients generated by the opening and closing of 500 kV disconnect switches. Transients or spurious signals caused by induction from 60 Hz fault currents, or by the energization or deenergization of DC contactor coils, or relay coils has fairly well been documented. Because of this, the main attention of this paper will be given to the subject of high frequency transients generated by multiple restrikes in an arc or in corona. This paper will discuss the variour tests made, and the results of the tests are tabulated.